Thread: Multiple EGR Codes

Wow forget the transmission issues I was having! My 99 Grand Prix GT started surging at highway speeds mainly when it was going up a hill. I hooked my code reader up and come up with multiple EGR codes. They include P1404, P0405 (twice) and P0404. Looking them up to try and find possible solutions has almost been impossible. Any ideas?

P0405 Exhaust Gas Recirculation Sensor A Circuit Low

P0404 Exhaust Gas Recirculation Circuit Range/Performance - DTC Code

Read those, should give you an idea of what you need to do to fix the issue.

Thanks. It's all a little above my head but, unless I pay someone money I don't have, I gotta figure it out and they are detailed enough I just might be able to.

all them codes lead to a bad egr valve, or bad wires to the valve. id start there.

I'm gonna check the wires first. I replaced the egr valve little over a year ago when I got the first P1404 code. Reset the service engine light but it came back. It went away when the weather warmed up but came back when winter hit again. When the car started surging I checked and came up with the other codes.

this link says that code is for a stuck egr, the wires may be bad if you changed the egr already.

DTC P1404 Exhaust Gas Recirculation (EGR) Closed Position Performance


Circuit Description
This diagnostic tests for an EGR valve that is stuck open. The PCM determines that the EGR valve is stuck open if the actual EGR position and the learned closed EGR position vary by more than a predetermined value. The PCM tests for a stuck valve when the desired EGR position is at 0%. The PCM commands the EGR valve to 100% during certain driving conditions in order to clear a possible restriction from the EGR valve if the PCM determines that the valve is stuck open. The PCM retests for a stuck valve when the desired EGR position returns to 0%. A failure timer increments if the stuck EGR valve condition is still present. This DTC sets when the timer reaches a predetermined value.

Conditions for Running the DTC

I know this is a stretch, but did you put a new EGR in or a used one? I had the same code on my GP and replaced it with a junkyard part. Lasted about a week before giving the same code again. Picked up another junkyard one, and it seemed to be doing better. Still cheaper to buy two than to buy a new one.

Replaced with a new one through an online parts store. Taking it to a mechanic soon to get looked at since my code reader doesn't have live readings.

Ok so just got it back from the mechanic and everything checked out good. No voltage issues. EGR works. Nothing blocking the valve. The machanic recommended getting the update from the dealership and that could possibly clear all the egr codes.

Apparently it's just an update in the programming. I was told about it over a year ago when I first had the P1404 code appear.

dealer pcm re flash, installs the latest up grades/programming for the engine. this only works for a stock pcm. if you let them do this to a tuned pcm, say bye bye to said tune because they will make it stock again.


had to have it done on my gmc truck.

I'm completely stock, as far as I know, so I don't need to worry about that.

There's no emissions here in ks either but I'm not able to play around until I get a different daily driver.